This application relates to a powered flowmeter valve and particularly to an automated powered flowmeter valve control for monitoring and controlling the flow of fluids.
Fluid control systems are widely used to supply a particular fluid to a load device. With various applications and processes, close and accurate control of the fluid flow is required. Further, if the fluid flow deviates in any significant manner, resetting response must be rapid in many applications. A typical example of systems requiring accurate metering of gases exists in gas fired combustion units, particularly for metal hardening furnaces. In such units, gases are often mixed and supplied to generate a suitable hardening atmosphere. Nitrogen and methanol are widely used with present day hardening furnaces. Controlled mixing of the gases and introduction into the furnace in an accurately controlled ratio is required for safe and efficient operation. If for any reason the gas mixture deviates from a pre-determined level, the system should be shut down by closure of an appropriate valve. The actual flow of the gases such as nitrogen may vary with various environmental conditions. The control unit should provide a rapid response to reset the respective gas flows and the like. The assignee of this application has a long history of supplying high quality flowmeters for accurately monitoring and controlling the flow of gas and other fluids to a high degree of accuracy. U.S. Patents issued to the assignee which disclose typical flowmeters having an automated control signal and a visual readout of the status of the flow condition include U.S. Pat. No. 4,774,676 which issued Sep. 27, 1988 and U.S. Pat. No. 4,864,870 which issued Sep. 12, 1989. Other flowmeter devices are available and disclosed in prior art such as disclosed in the above patents.
Although prior art systems have been used heretofore and recognized as providing satisfactory performance in various applications, there is a need for an improved system for accurate and rapid readjustment of a flow control valve coupled to a metered flow system to accurately hold the flow within close parameters, as well as permitting shutdown in limit positions indicative of an abnormal flow and a malfunction or failure within the metering system.